FORM AND STRUCTURE OF MICROBES 65 



the same author in the digestive tube of an annelid (Bryodrilus) 

 ought rather to be considered as a mould. 



To-day one can agree neither with those who affirm that 

 there is no nucleus nor with those who describe a well-defined 

 nucleus. In reality, the bacteria possess a diffuse nucleus. 

 Instead of forming a mass with sharp contours, the chromatin 

 is scattered through the protoplasm in the form of granules 

 quite distinct from the metachromatic granules. 



Long ago Weigert maintained that the nucleus is, as it were, 

 melted or dissolved in the cytoplasm, for it is precisely the 

 nuclear stains which stain the bacteria best; Biitschli con- 

 sidered that the cytoplasm of bacteria is reduced to a thin 

 layer lying in apposition with the membrane, and that the 

 bacterium, far from lacking a nucleus, is in reality almost all 

 nucleus. Further, what purpose would a large quantity of 

 cytoplasm fulfil, cytoplasm whose special function is nutritive ? 

 Bacteria are parasitic, and absorb their nourishment ready 

 prepared. Their chief business is to multiply, to increase in 

 numbers ; it is quite natural for them, therefore, to possess an 

 enormous nucleus like the spermatozoa and the embryonic 

 cells, so much so that one might even say that bacteria are 

 " free nuclei." 



Schaudinn has furnished a brilliant support to these ideas 

 by means of his observations on the largest known bacillus, the 

 Bacillus Biitschlii, found by him in the intestine of cockroaches. 

 The chromatin granules are scattered through the protoplasm ; 

 to produce the two spores they come together, and the 

 chromatin condenses at the two ends. The condition of a 

 diffuse nucleus is no less evident in the B. maximus buccalis of 

 Swellengrebel. 



The diffuse nucleus is not confined to bacteria. There are 

 several protozoa which normally possess a well-defined nucleus, 

 but at certain moments in development or in certain conditions 

 of nutrition this may be seen changing into a diffuse nucleus. 

 The diffused nuclei have been called by R. Hertwig chromidia. 

 Several varieties exist, and the nucleus of B. Biitschlii, like the 

 nuclei of bacteria, in general should be considered as consisting 



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